[英]Hibernate: persist entity with bidirectional many-to-one mapping with join table - org.hibernate.PropertyValueException
[英]How to Persist an Entity with Two Many-to-One Bidirectional Dependencies in Hibernate?
我在數據庫中有以下關系實體:
Table A <-- (One-to-Many) --> Table B
Table B <-- (One-to-Many) --> Table C
Table B <-- (Many-to-One) --> Table J
Table C <-- (Many-to-One) --> Table J
表 B 包含表 A 和 J 的外鍵。表 C 包含表 B 和 J 的外鍵。
注意:表 B 和 C 都包含外鍵引用 (TABLE_J_ID),引用表 J。
如您所見,表 B 和 C 都與表 J 具有多對一關系。因此,我創建了以下雙向實體:
@Entity
@Table(name="TableA")
public class TableA {
@Id
// Generates via a sequence object
private Integer id;
@OneToMany(mapped="tableATableB", cascade=CascadeType.All, orphanRemoval=true)
private Set<TableB> tableBs = new LinkedHashSet<TableB>();
public void addTableB(TableB b) {
this.tableBs.add(b);
b.setTableATableB(this);
}
}
@Entity
@Table(name="TableB")
public class TableB {
@Id
// Generates via a sequence object
private Integer id;
@ManyToOne
@JoinColumn(name="TABLE_J_ID")
private TableJ tableJTableB;
@ManyToOne
@JoinColumn(name="TABLE_A_ID")
private TableA tableATableB;
@OneToMany(mapped="tableBTableC", cascade=CascadeType.All, orphanRemoval=true)
private Set<TableC> tableCs = new LinkedHashSet<TableC>();
public void addTableC(TableC c) {
this.tableCs.add(c);
b.setTableBTableC(this);
}
}
@Entity
@Table(name="TableJ")
public class TableJ {
@Id
// Generates via a sequence object
private Integer id;
@OneToMany(mapped="tableJTableB", cascade=CascadeType.All)
private Set<TableB> tableBs = new LinkedHashSet<TableB>();
@OneToMany(mapped="tableJTableC", cascade=CascadeType.All)
private Set<TableC> tableCs = new LinkedHashSet<TableC>();
public void addTableB(TableB b) {
this.tableBs.add(b);
b.setTableJTableB(this);
}
public void addTableC(TableC c) {
this.tableCs.add(c);
b.setTableJTableC(this);
}
}
@Entity
@Table(name="TableC")
public class TableC {
@Id
// Generates via a sequence object
private Integer id;
@ManyToOne
@JoinColumn(name="TABLE_J_ID")
private TableJ tableJTableC;
@ManyToOne
@JoinColumn(name="TABLE_B_ID")
private TableB tableBTableC;
}
對象圖/樹的構建方式:
TableA tableA = new TableA();
// Get a list of TableB's (bList) from an external call
// THIS BASICALLY ADDS TABLE B's to TABLE A and TABLE J
for (TableB b : bList) {
TableJ j = new TableJ();
j.addTableB(b);
tableA.addTableB(b);
}
// Get a list of TableC's (cList) from an external call
// THIS BASICALLY ADDS TABLE C's to TABLE B and TABLE J
for (TableC c : cList) {
for (TableB b : tableA.getTableBs()) {
// Iterate through bList and find a match per some logic
if (/* some logic to find a corresponding TableB */) {
TableJ j = new TableJ();
j.addTableC(c);
b.addTableC(c);
}
}
}
當我執行代碼時,出現以下錯誤:
**Unexpected error occurred in scheduled task.: org.springframework.dao.InvalidDataAccessApiUsageException: org.hibernate.TransientPropertyValueException: object TableB.tableJTableB -> class TableJ; nested exception in java.lang.IllegalStateException: org.hibernate.TransientPropertyValueException: object references an unsaved transient instance - save the transient instance before flushing: TableB.tableJTableB -> class TableJ
Caused by: java.lang.IllegalStateException: org.hibernate.TransientPropertyValueException: object references an unsaved transient instance - save the transient instance before flushing: TableB.tableJTableB -> class TableJ**
有人可以告訴我這是什么問題嗎?
問題是:
首先插入A。 然后 A_ID 用作 B 中的 FK。插入 B。 B 還需要 J_ID FK,但 J 尚未存儲 = 瞬態。
JPA 創建插入的順序應該改變。 創建 B、C 需要 J_ID。 在將 J 添加到 B、C 之前堅持 J。
for (TableB b : bList) {
TableJ j = new TableJ();
em.persist(j)
j.addTableB(b);
tableA.addTableB(b);
}
還有另一個循環
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